This invention pertains to a polynorbornene type molded product having a film of vinylidene chloride type resin and/or unsaturated nitrile type resin thereon and to the method of making it. More specifically, the invention herein pertains to a polynorbornene molded product and method of its manufacture in which the odor characteristic of the norbornene type monomer's ring-opened polymer is curbed and the product has excellent lustre and weather resistance.
By ring-opening polymerization of a norbornene type monomer within a mold by means of the reaction injection molding (RIM) method it is possible to obtain ring-opened polymers with mechanical strength, heat resistance, and water resistance, etc. However, when the ring-opened polymer of the norbornene type monomer is used, the unreacted monomer often tends to remain within the final molded product. For that reason, a distinct odor is emitted. Therefore, the prior art product is generally not used in an environment where the odor becomes a problem, such as in a closed room. Also, the color of the prior art polynorbornene type molded product is usually yellow or brown. Even when dyes are added, the color tone tends to change as the time passes.
In the past, in order to improve the surface condition of the polynorbornene type molded product, methods have been proposed in which paint was applied, as in the disclosure Japanese KOKAI 63-23971, or colored plastic sheets or printed sheets were laminated to the polymer product. In spite of the many different ways that were tried, it was difficult to curb the distinct odor. Problems with the tried systems abounded. For instance, with water-soluble paints, there was a problem in that the painted film could not be formed easily. On the other hand, in the case of plastic sheets, since many adhere poorly to the polynorbornene type molded product, it was difficult to obtain practical composite materials.
It was discovered earlier that by providing a layer of a film or sheet of an olefin type polymer or hydrocarbon type thermoplastic elastomer on the surface of the base material made of polynorbornene, it was possible to obtain a composite material with good surface adhesion, improved surface conditions, and curbed odor. The inventors submitted a patent application, identified as Japanese Application No. 63-171038. However, their advances were still insufficient in terms of prevention of odor.